Control of microorganisms with trihalovinylthiocyanate



United States Patent Office 3,253,981 Patented May 31, 1966 3,253,981 CONTROL OF MICROORGANISMS WITH TRIHALOVIN YLTHIOCYAN ATE Edward D. Weil, Lewiston, Emil J. Geering, Grand Island, and Keith J. Smith, Lockport, N.Y., assignors to Hooker Chemical Corporation, Niagara Falls, N.Y., a corpo- This is a division of application Serial No. 258,596, filed February 14, 1963, now Patent No. 3,205,247 issued September 7, 1965, which is a continuation-in-part of our .co-pending applications, Serial No. 800,981, filed March 23, 1959, and Serial No. 93,298, filed March 6, 1961.

This invention comprises a new and useful composition of matter, trihalovinyl thiocyanate, especially trichlorovinyl thiocyanate, an active biotoxicant.

Synthetic routes to trichlorovinyl thiocyanate have hitherto been lacking. The replacement of a chlorine atom on tetr'achloroethylene by reaction with a thiocyanate fails to occur, in keeping with the usual inertness of the vinylic chlorine atoms. The chlorination of vinyl thiocyanate would give an addition product, not substitution of hydrogens, in keeping with the normal mode of reaction of ethylene with chlorine.

Our discovery of new synthetic intermediates, having novel modes of reaction, has now made possible the convenient and inexpensive synthesis of tn'halovinyl thiocyanate. These compounds are active against microorganisms, e.g., fungi, bacteria, nematodes and other microscopic organisms, which may be detrimental to higher plant and/or animal life. Therefore, they may be referred to as biotoxicants, which compounds control and prevent the growth of such microorganisms when applied to the sites thereof. Specifically, we have found that our new intermediate, tetrachloroethanesulfenyl chloride, which is the subject of SN. 233,814, filed October 29, 1962, which is also a continuation-in-part of SN. 800,981, undergoes reaction with two or more molar equivalents of a metal cyanide to yield trichlorovinyl thiocyanate.

This reaction is contrary to that observed by Brintzinger (Chemische Berichte, 87,319 (1954)) with CH ClSCl, which yielded CH (CN)SCN upon reaction with KCN. By analogy with the prior art, a trichloro-l-cyanoethyl thiocyanate would be expected, but is not observed to be formed.

' The process of the invention may be carried out at temperature in the range of -40 degrees centigrade to the boiling point of the tetrachloroethanesulfenyl chloride, but is preferably performed in the range of degrees to +140 degrees centigrade. At lower temperatures the. reaction proceeds but may be sluggish. At higher temperatures thermal decomposition may become excessive.

The cyanide employed may be an alkali cyanide or an alkaline earth'cyanide, preferably the former and, for economic reasons, preferably sodium or potassium cyanide.

While not necessary, the use of a solvent for the cyanide is preferred because of its favorable effect on the rate and completeness of reaction. Suitable solvents are, for example, water, alcohols (particularly lower aliphatic alcohols much as methanol and alkoxy-alkanols such as Cellosolve), dimethylformamide, dimethylacetamide, dimethylsulfoxide, lower aliphatic ketones such as acetone, and lower aliphatic nitriles such as acetonitrile.

Pressures of atmospheric or near atmospheric are preferred although higher or lower pressures may be employed. The sulfeny-l chloride may be added to the cyanide, the cyanide may be added to the sulfenyl chloride compounds, or both may be added simultaneously to the solvent. Agitation is advantageous during the course of the admixture. The product is conveniently isolated by fractional distillation of the organic phase of the reaction mixture.

Trichlorovinyl thiocyanate is a liquid of boiling point 50-55 degrees cent-igrade (1.5 millimeters), with a characteristic penetrating odor. Its infrared spectrum confirms the presence of the carbon-to-carbon double bond and the thiocyanate functional group.

To further make clear the process of our invention, the following example is given:

Example Three hundred ninety eight parts by weight of his (tetrachloroethyl) disulfide (prepared by the reaction of trichloroethylene with sulfur monochloride as described in copending application S.N. 800,933, filed March 23, 1959, now US. 3,088,818), is cooled to minus 20 degrees centigrade and is treated with gaseous chlorine with agitation and cooling to maintain this temperature. After the weight has increased to 469 parts, the mixture is allowed slowly to rise to room temperature, then is fractionated through a packed fractionating column of approximately three theoretical plates. The product taken off as a fraction boiling at 53 to 57 degrees centigrade (0.5 millimeters), is a malodorous yellow liquid having a specific gravity of 1.760 at 23 degrees centigrade, having the correct analysis for a tetrachloroe thanesulfenyl chloride.

Analysis.Calculated for C HCl S: Cl, 75.7%; S 13.6%. Found: Cl, 76.2%; S, 13.5%.

By gas chromatography over a 250 cm. column packed with silicone grease on 30-60 mesh inert siliceous support and maintained at degrees centigrade the product was resolved into two isomers. The one isomer having the shorter retention time comprised 83 percent of the mixture. It was identified as the 1,2,2,2-tetrachloroethanesulfenyl chloride by the fact that its nuclear magnetic resonance spectrum measured at 60 megacycles on a Varian A60 NMR spectrograph, showed a proton resonance at 344 cycles per second (relative to tetramethylsilane as standard), indicating less shielding of the proton compared to that in the other isomer. The other isomer, having the longer retention time, comprised 17 percent of the mixture. It was identified as the 1,1,2,2-tetrachloroethanesulfenyl chloride by the nuclear magnetic resonance spectrum which showed a proton resonance at 370 cycles per second (reactive to tetramethylsilane as standard) indicating greater shielding of the proton (as would be caused by a greater number of adjacent chlorine atoms), relative to the other isomer.

The bis(tetrachloroethyl) disulfide starting material was therefore a mixture of bis(l,2,2,2-tetrachloroethyl) disulfide, bis(1,1,2,2 tetrachloroethyl) disulfide and CHCl CCl SfiSCHCl-CCl A solution of 26 parts by weight of potassium cyanide in three hundred twenty parts of methanol was stirred at 0-10 degrees centigrade and 46.9 parts by weight of the tetrachloroethanesulfenyl chloride (prepared as described above) was added dropwise over one hour. Cooling was used to hold the temperature at 0-10 degrees centigrade. The reaction mixture was stirred for an hour after addition was complete, the methanol was stripped off under water aspirator vacuum, then water was added to dissolvethe inorganic salts and the heavy organic oil was separated and fractionated in a still to isolate the desired product in good yield as a red oil boiling at 50-55 degrees Centigrade (1.5 millimeters).

Analysis.-Calcd. for Found: Cl, 56.4%, N, 13.2%.

The remarkable nematocidal utility of trichlorovinyl thiocyanate is shown by the following test. Into soil infected with M eloidogyne incognita (a common nematode causative of root knot disease of tobacco, tomato, cucumber, etc.) was admixed trichlorovinyl thiocyanate at the rate of 0.1 gram of chemical per gallon of soil. After three days, healthy cucumber seedlings were transplanted into the treated soil and allowed to grow therein under greenhouse conditions. One month later, the cucumber plants were uprooted and their root systems were found to be entirely free of the galls which are characteristic symptoms of root knot disease, whereas in control experiments wherein the chemical was omitted, the roots were severely galled and the plants were badly stunted by nematode-produced root lesions. To give the same protective efiect as 0.1 gram of trichlorovinyl thiocyanate per gallon of soil, 1 gram of the commercial nematocide D-D mixture (dichloropropane-dichloropropene) per gallon of soil was required. A very high degree of fungicidal activity is also shown by trichlorovinyl thiocyanate as shown by the following test: soil heavily infested with spores of Pythium was admixed with trichlorovinyl thiocyanate at 50 p.p.m. Beans were planted therein and also in infested untreated soil for comparison. In the untreated soil, none of the beans emerged because of damping off, whereas in the treated soil, 100 percent of the beans emerged normally.

The compound of the invention is also bactericidal and/ or bacteriostatic, and, for example, was found to inhibit the growth of Escherichia coli and Staphylococcus aureus at 19 parts per million on nutrient agar.

When corresponding other halogenated reactants are employed, corresponding halogenated biotoxicants are obtained, e.g., the bromine derivatives.

Various modifications can be made to the above description and we do not wish to be limited thereto except as defined in the appended claims.

' We claim:

1'. A method for controlling microorganisms which comprises treating the locus of the microorganisms with a trihalovinyl thiocyanate in which the halogen is selected from the group consisting of chlorine annd bromine.

2. A method for controlling microorganisms which comprises treating the microorganisms with trichlorovinyl thiocyanate.

3. A method for controlling fungi which comprises treating the fungi with trichlorovinyl thiocyanate.

4. A method for controlling bacteria which comprises treating the bacteria with trichlorovinyl thiocyanate.

5. A method for controlling nematodes which comprises treating the nematodes with trichlorovinyl thiocyanate.

References Cited by the'Examiner UNITED STATES PATENTS 2,214,971 9/ 1940 Muller 260-454 2,572,564 10/1951 Himel et al. 260-454 2,573,973 11/1951 Johnson et a1 260-454 2,613,221 10/1952 Ladd et al. 260-454 2,650,240 8/1953 Olin 260-454 2,671,799 3/ 1954 Miller 260-454 2,859,235 11/1958 Schmidt et al. 260-454 2,867,562 1/1959 Lamb 167-22 2,913,368 11/1959 Birum 167-22 3,010,947 11/ 1961 Hwa 260-454 3,170,942 2/ 1965 Fancher et al 260-454 OTHER REFERENCES Childs et al., J. Chem. Soc. (London), vol. of 1948, pp. 21802183.

Mardehanyan et al., Chem. Abstr., vol. 51, p. 124l2f (1957).

Prochazka et al., Collections Czech. Chem. Communs., vol. 14, pp. 156-161 (1949).

Schmidt et al., Ann. der Chem., vol. 560, pp. 222-231 (1948).

LEWIS GOTTS, Primary Examiner.

RICHARD L. HUFF, Assistant Examiner. 

1. A METHOD FOR CONTROLLING MICROORGANISMS WHICH COMPRISES TREATING THE LOCUS OF THE MICROORGANISMS WITH A TRIHALOVINYL THIOCYANATE IN WHICH THE HALOGEN IS SELECTED FROM THE GROUP CONSISTING OF CHLORINE ANND BROMINE. 